The Sunday Times newspaper quoted Ian Rankin, a fellow author and neighbor of Rowling's, as saying the creator of the "Harry Potter" books is turning to crime fiction.
"My wife spotted her writing her Edinburgh criminal detective novel," the newspaper, which was available late Saturday, quoted Rankin as telling a reporter at an Edinburgh literary festival.
"It is great that she has not abandoned writing — or Edinburgh cafes," said Rankin, who is known for his own police novels set in the historic Scottish city.
Rowling famously wrote initial drafts of the Potter story in the Scottish city's cafes. Back then, she was a struggling single mother who wrote in cafes to save on the heating bill at home.
Now she's Britain's richest woman — worth $1 billion, according to Forbes magazine — and her seven Potter books have sold more than 335 million copies worldwide.
In an interview with The Associated Press last month, Rowling said she believed she was unlikely to repeat the success of the Potter series, but confirmed she had plans to work on new books.
"I'll do exactly what I did with Harry — I'll write what I really want to write," Rowling said.
The office of Rowling's literary agent, Christopher Little, was not immediately available to comment late Saturday.